Communication method, terminal device, and network device

ABSTRACT

Embodiments of this application provide a communication method, a terminal device, and a network device. Referring to the method, blind detection of a terminal device can be performed in different scheduling periods based on a maximum number of blind detection in a preset time period, thereby helping to reduce energy consumption that is caused to a terminal device by blind detection, and reduce blind detection complexity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2018/101892, filed on Aug. 23, 2018, which claims priority toChinese Patent Application No. 201710808057.8, filed on Sep. 8, 2017.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the communications field, and morespecifically, to a communication method, a terminal device, and anetwork device.

BACKGROUND

Downlink control information (DCI) is carried by a physical downlinkcontrol channel (PDCCH), and may be used to carry resource configurationinformation of a terminal device and other control information. Becausea plurality of PDCCHs sent to a plurality of terminal devices may betransmitted in one scheduling period, a terminal device needs to receive(to be specific, blindly detect or blindly decode), from the pluralityof PDCCHs, a PDCCH sent to the terminal device, to obtain DCI. Theterminal device demodulates, based on an indication of the DCI, at acorresponding resource location, a physical downlink shared channel(PDSCH) that belongs to the terminal device.

In long term evolution (LTE) systems, a subframe is used as a schedulingperiod for sending PDCCHs, so as to perform resource scheduling. Amaximum number of blind detection by a terminal device in one subframeis defined in LTE. Such maximum number may be 44, for example. In otherwords, in one subframe, the terminal device may perform a maximum numberof 44 blind detections. Also, in LTE, a scheduling period is the same asa blind detection period.

However, using one subframe as a time length of a scheduling period mayfail to meet requirements of some services, such as ultra-reliable andlow latency communications (URLLC), which has a relatively highrequirement on latency. Therefore, it is desired that the schedulingperiod can be flexibly adjusted based on a service type, to performresource scheduling for a terminal device. For example, scheduling maybe performed by using a slot as a scheduling period, or using a symbolas a scheduling period.

On the other hand, if blind detection is performed in all schedulingperiods based on a same maximum number of blind detection, for aterminal device that has a relatively short scheduling period (forexample, a mini-slot), the number of blind detection performed by theterminal device in one slot may be multiplied. This greatly increasesenergy consumption caused by blind detection of the terminal device, andmay increase blind detection complexity of the terminal device.

SUMMARY

This application provides a communication method, a terminal device, anda network device, so that blind detection can be performed in differentscheduling periods based on a maximum number of blind detection in apreset time period, thereby helping to reduce energy consumption that iscaused to a terminal device by blind detection, and reduce blinddetection complexity of the terminal device.

According to a first aspect, a communication method is provided. Themethod includes: determining, by a terminal device, a maximum number ofblind detection in a first time unit, where the first time unit is oneor more symbols; and performing, by the terminal device, physicaldownlink control channel blind detection in the i^(th) blind detectionoccasion, where the first time unit includes N blind detectionoccasions, and a number of physical downlink control channel blinddetection performed by the terminal device in the N blind detectionoccasions is less than or equal to the maximum number of blinddetection, where i and N are positive integers, i≤N, and N≥2.

According to the foregoing technical solution, the terminal device mayperform blind detection in a plurality of blind detection occasionsbased on the maximum number of blind detection in the first time unit,so that blind detection can be performed in different scheduling periodsbased on the same maximum number of blind detection. Further, when anetwork device sends a plurality of physical downlink control channelsto the terminal device, the terminal device does not need to performblind detection separately based on different scheduling periods. Thishelps to reduce energy consumption that is caused to the terminal deviceby blind detection, and reduce blind detection complexity of theterminal device.

Optionally, the first time unit is one slot.

With reference to the first aspect, in some implementations of the firstaspect, the method further includes: receiving, by the terminal device,configuration information, where the configuration information is usedto determine a number of blind detection in each blind detectionoccasion in the first time unit.

The terminal device may determine the number of blind detection in eachof the N blind detection occasions in the first time unit based on theconfiguration information, to perform physical downlink control channelblind detection successively in the N blind detection occasions based onthe number of blind detection.

The number of blind detection in each blind detection occasion may bedetermined based on an aggregation level that is configured by thenetwork device and that is corresponding to each downlink controlinformation format, and a quantity of candidate physical downlinkcontrol channels at each aggregation level, or may be determined by theterminal device based on the maximum number of blind detection and aquantity of blind detection occasions in the first time unit.

With reference to the first aspect, in some implementations of the firstaspect, the performing, by the terminal device, physical downlinkcontrol channel blind detection in the i^(th) blind detection occasionincludes: performing, by the terminal device, physical downlink controlchannel blind detection in the i^(th) blind detection occasion based onfirst information, where the first information includes at least one ofthe following: configuration information for a control resource set, asearch space type, a format of downlink control information, anaggregation level corresponding to the downlink control information, andserial numbers of start control channel elements of a plurality ofcandidate physical downlink control channels at a same aggregationlevel.

It should be understood that, the first information may be obtained fromthe configuration information, or may be predefined. This is not limitedin this application.

Further, the terminal device may perform blind detection in the i^(th)blind detection occasion based on at least one of the foregoing factors.In this way, an order in which the terminal device performs blinddetection can be determined from different perspectives based ondifferent factors, to be applicable to different scenarios.

Optionally, the first information includes the configuration informationfor a control resource set, and a plurality of control resource sets aredistributed in the i^(th) blind detection occasion; and the performing,by the terminal device, physical downlink control channel blinddetection in the i^(th) blind detection occasion based on configurationinformation for a physical downlink control channel includes:performing, by the terminal device, physical downlink control channelblind detection successively on the plurality of control resource setsbased on a descending order of priorities of the plurality of controlresource sets in the i^(th) blind detection occasion.

Optionally, the first information includes the search space type, andthe performing, by the terminal device, physical downlink controlchannel blind detection in the i^(th) blind detection occasion based onfirst information includes: performing, by the terminal device, physicaldownlink control channel blind detection successively in a plurality ofsearch spaces based on a priority order of search space types in thei^(th) blind detection occasion, where the search space types include acommon search space and a user-specific search space.

Optionally, the first information includes the format of the downlinkcontrol information, and there are a plurality of downlink controlinformation formats in the i^(th) blind detection occasion; and theperforming, by the terminal device, physical downlink control channelblind detection in the i^(th) blind detection occasion based on firstinformation includes: successively performing, by the terminal device,physical downlink control channel blind detection in the i^(th) blinddetection occasion based on a priority order of the plurality ofdownlink control information formats.

Optionally, the first information includes the aggregation level, andthere are a plurality of aggregation levels corresponding to downlinkcontrol information that waits to be blindly detected in the i^(th)blind detection occasion; and the performing, by the terminal device,physical downlink control channel blind detection in the i^(th) blinddetection occasion based on first information includes: performing, bythe terminal device, physical downlink control channel blind detectionin the i^(th) blind detection occasion based on an ascending order or adescending order of the aggregation levels.

Optionally, the first information includes the serial numbers of thestart control channel elements of the candidate physical downlinkcontrol channels, and there are a plurality of candidate physicaldownlink control channels at a same aggregation level corresponding todownlink control information that waits to be blindly detected in thei^(th) blind detection occasion; and the performing, by the terminaldevice, physical downlink control channel blind detection in the i^(th)blind detection occasion based on first information includes:performing, by the terminal device, physical downlink control channelblind detection in the i^(th) blind detection occasion based on adescending order or an ascending order of serial numbers of the startcontrol channel elements of the plurality of candidate physical downlinkcontrol channels at the same aggregation level.

Therefore, the network device may send at least one physical downlinkcontrol channel in the plurality of blind detection occasions accordingto any one or more of the foregoing rules, and the terminal device mayperform blind detection according to the one or more of the foregoingrules. When the network device and the terminal device respectively senda physical downlink control channel and perform blind detectionaccording to a same rule, the terminal device can detect, within alimitation of the maximum number of blind detection, the physicaldownlink control channel sent by the network device. This can not onlyavoid a detection omission of the terminal device, but also reduceenergy consumption caused by blind detection of the terminal device andreduce blind detection complexity.

According to a second aspect, a communication method is provided. Themethod includes: sending, by a network device, configurationinformation, where the configuration information is used to indicate anumber of blind detection in each of N blind detection occasions in afirst time unit, the first time unit is one or more symbols, the firsttime unit includes the N blind detection occasions, N is a positiveinteger, and N≥2; and sending, by the network device, at least onephysical downlink control channel in the i^(th) blind detectionoccasion, where i is a positive integer, and i≤N.

According to the foregoing technical solution, the network device sendsthe configuration information to a terminal device, so that the terminaldevice determines the number of blind detection in each of the N blinddetection occasions in the first time unit, to perform blind detectionin the N blind detection occasions. Therefore, the terminal device canperform blind detection in different scheduling periods based on a samemaximum number of blind detection. Further, when the network devicesends a plurality of physical downlink control channels to the terminaldevice, the terminal device does not need to perform blind detectionseparately based on different scheduling periods. This helps to reduceenergy consumption that is caused to the terminal device by blinddetection, and reduce blind detection complexity of the terminal device.

Optionally, the first time unit is one slot.

With reference to the second aspect, in some implementations of thesecond aspect, the sending, by the network device, at least one physicaldownlink control channel in the i^(th) blind detection occasionincludes: sending, by the network device, the at least one physicaldownlink control channel in the i^(th) blind detection occasion based onfirst information, where the first information includes at least one ofthe following: configuration information for a control resource set, asearch space type, a format of downlink control information, anaggregation level corresponding to the downlink control information, andserial numbers of start control channel elements of a plurality ofcandidate physical downlink control channels at a same aggregationlevel.

Optionally, the first information includes the configuration informationfor a control resource set, and a plurality of control resource sets aredistributed in the i^(th) blind detection occasion; and the sending, bythe network device, at least one physical downlink control channel inthe i^(th) blind detection occasion includes: selecting, by the networkdevice, an available control resource set in the i^(th) blind detectionoccasion based on a descending order of priorities of the plurality ofcontrol resource sets, and sending the at least one physical downlinkcontrol channel by using the available control resource set.

The network device may send the at least one physical downlink controlchannel in the N blind detection occasions based on at least one of theforegoing factors. In this way, a sending order of physical downlinkcontrol channels can be determined from different perspectives based ondifferent factors, to be applicable to different scenarios.

Optionally, the first information includes the search space type, andthe sending, by the network device, at least one physical downlinkcontrol channel in the i^(th) blind detection occasion includes:selecting, by the network device, an available search space in thei^(th) blind detection occasion based on a priority order of searchspace types, and sending the at least one physical downlink controlchannel by using the available search space.

Optionally, the first information includes the format of the downlinkcontrol information, and a plurality of downlink control informationformats need to be sent in the i^(th) blind detection occasion; and thesending, by the network device, at least one physical downlink controlchannel in the i^(th) blind detection occasion includes: successivelysending, by the network device, the at least one physical downlinkcontrol channel in the i^(th) blind detection occasion based on apriority order of the plurality of downlink control information formats.

Optionally, the first information includes the aggregation level, and aplurality of aggregation levels are configured for a same downlinkcontrol information format in the i^(th) blind detection occasion; andthe sending, by the network device, at least one physical downlinkcontrol channel in the i^(th) blind detection occasion includes:selecting, by the network device, an available aggregation level basedon a descending order or an ascending order of the plurality ofaggregation levels corresponding to the same downlink controlinformation format in the i^(th) blind detection occasion, and sendingthe at least one physical downlink control channel by using theavailable aggregation level.

Optionally, the first information includes the serial numbers of thestart control channel elements of the plurality of candidate physicaldownlink control channels at the same aggregation level, and there are aplurality of candidate physical downlink control channels at a sameaggregation level corresponding to downlink control information thatwaits to be blindly detected in the i^(th) blind detection occasion; andthe sending, by the network device, at least one physical downlinkcontrol channel in the i^(th) blind detection occasion includes:determining, by the network device, an available candidate physicaldownlink control channel based on an ascending order or a descendingorder of serial numbers of the start control channel elements of theplurality of candidate physical downlink control channels, and sendingthe at least one physical downlink control channel by using theavailable candidate physical downlink control channel.

Therefore, the network device may send the at least one physicaldownlink control channel in the plurality of blind detection occasionsaccording to any one or more of the foregoing rules, and the terminaldevice may perform blind detection according to the one or more of theforegoing rules. When the network device and the terminal devicerespectively send a physical downlink control channel and perform blinddetection according to a same rule, the terminal device can detect,within a limitation of the maximum number of blind detection, thephysical downlink control channel sent by the network device. This cannot only avoid a detection omission of the terminal device, but alsoreduce energy consumption caused by blind detection of the terminaldevice and reduce blind detection complexity.

According to a third aspect, a terminal device is provided. The terminaldevice has functions for implementing the terminal device in the methoddesign of the first aspect. These functions may be implemented by usinghardware, or may be implemented by executing corresponding software byhardware. The hardware or software includes one or more unitscorresponding to the functions.

According to a fourth aspect, a network device is provided. The networkdevice has functions for implementing the network device in the methoddesign of the second aspect. These functions may be implemented by usinghardware, or may be implemented by executing corresponding software byhardware. The hardware or software includes one or more unitscorresponding to the functions.

According to a fifth aspect, a terminal device is provided. The terminaldevice includes a transceiver, a processor, and a memory. The processoris configured to control the transceiver to send and receive a signal,the memory is configured to store a computer program, and the processoris configured to invoke the computer program from the memory and run thecomputer program, so that the terminal device performs the method in thefirst aspect.

According to a sixth aspect, a network device is provided. The networkdevice includes a transceiver, a processor, and a memory. The processoris configured to control the transceiver to send and receive a signal,the memory is configured to store a computer program, and the processoris configured to invoke the computer program from the memory and run thecomputer program, so that the network device performs the method in thesecond aspect.

According to a seventh aspect, a communications apparatus is provided.The communications apparatus may be the terminal device in the foregoingmethod design, or a chip disposed in the terminal device. Thecommunications apparatus includes: a memory, configured to storecomputer executable program code; a communications interface; and aprocessor. The processor is coupled to the memory and the communicationsinterface. The program code stored in the memory includes aninstruction. When the processor executes the instruction, thecommunications apparatus is enabled to perform the method that isperformed by the terminal device in any one of the first aspect or thepossible designs of the first aspect.

According to an eighth aspect, a communications apparatus is provided.The communications apparatus may be the network device in the foregoingmethod design, or a chip disposed in the network device. Thecommunications apparatus includes: a memory, configured to storecomputer executable program code; a communications interface; and aprocessor. The processor is coupled to the memory and the communicationsinterface. The program code stored in the memory includes aninstruction. When the processor executes the instruction, thecommunications apparatus is enabled to perform the method that isperformed by the network device in any one of the second aspect or thepossible designs of the second aspect.

According to a ninth aspect, a computer program product is provided. Thecomputer program product includes computer program code. When thecomputer program code is run on a computer, the computer is enabled toperform the methods in the foregoing aspects.

According to a tenth aspect, a computer readable medium is provided. Thecomputer readable medium stores computer program code. When the computerprogram code is run on a computer, the computer is enabled to performthe methods in the foregoing aspects.

According to an eleventh aspect, a chip is provided. The chip includes aprocessor and a memory. The memory is configured to store a computerprogram, and the processor is configured to invoke the computer programfrom the memory and run the computer program, where the computer programis used to implement the methods in the foregoing aspects.

In some possible implementations, the configuration information includesat least one of the following: at least one downlink control informationDCI format in each blind detection occasion, an aggregation levelcorresponding to each DCI format, a quantity of a plurality of candidatephysical downlink control channels at a same aggregation level, aquantity N of the blind detection occasions in the first time unit, andthe total number of blind detection in each blind detection occasion.

In some possible implementations, the control resource sets areperiodically distributed in one slot, and control resource sets in anytwo slots have same start locations and same duration.

In some possible implementations, the control resource sets areperiodically distributed in one slot, and control resource sets in atleast two slots have different start locations and/or differentduration.

In some possible implementations, one control resource set is in oneslot. In other words, one control resource set does not span two slots.

In some possible implementations, a priority of the common search spaceis higher than a priority of the user-specific search space.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a communications system in which acommunication method according to embodiments of this application can beperformed;

FIG. 2 is a flow diagram of a communication method according to anembodiment of this application;

FIG. 3 is a schematic diagram of a blind detection period;

FIG. 4 is a schematic diagram of a control resource set configuration;

FIG. 5 is another schematic diagram of a control resource setconfiguration;

FIG. 6 is still another schematic diagram of a control resource setconfiguration;

FIG. 7 is yet another schematic diagram of a control resource setconfiguration;

FIG. 8 is another schematic diagram of a blind detection period;

FIG. 9 is a schematic block diagram of a terminal device according to anembodiment of this application;

FIG. 10 is a schematic structural diagram of a terminal device accordingto an embodiment of this application;

FIG. 11 is a schematic block diagram of a network device according to anembodiment of this application; and

FIG. 12 is a schematic structural diagram of a network device accordingto an embodiment of this application.

DESCRIPTION OF EMBODIMENTS

The following describes technical solutions of this application withreference to accompanying drawings.

The technical solutions in embodiments of this application may beapplied to various communications systems, such as global system formobile communications (GSM) system, code division multiple access (CDMA)system, wideband code division multiple access (WCDMA) system, generalpacket radio service (GPRS) system, long term evolution (LTE) system,LTE frequency division duplex (FDD) system, LTE time division duplex(TDD) system, universal mobile telecommunication system (UMTS),worldwide interoperability for microwave access (WiMAX) communicationssystem, and fifth generation (5G) communication systems or new radio(NR) systems that are in development.

For ease of understanding of the embodiments of this application, acommunications system to which the embodiments of this application areapplicable is first described in detail with reference to FIG. 1. FIG. 1is a schematic diagram of a communications system 100 to which areference signal sending and receiving method in an embodiment of thisapplication is applicable. As shown in FIG. 1, the communications system100 may include a network device 102 and terminal devices 104 to 114.

It should be understood that, the network device 102 may be anycommunication device that has wireless sending/receiving and processingfunctionalities, or a component of such device that provides the abovefunctionalities, such as a set of microchips. Examples of the networkdevice 102 include, and not limited to: a base station (such as a NodeB(NodeB), an evolved NodeB (eNodeB)), or a network device (such as atransmission point (TP), a transmission reception point (TRP), a basestation, or a small cell device) in a 5th generation (5G) communicationssystem); a network device in a future communications system; an accessnode, a wireless relay node, or a wireless backhaul node in a wirelessfidelity (Wi-Fi) system; and the like.

The network device 102 may communicate with a plurality of terminaldevices (for example, the terminal devices 104 to 114 shown in thefigure).

It should be understood that the terminal device may also be referred toas user equipment (UE), an access terminal, a subscriber unit, asubscriber station, a mobile station, a mobile console, a remotestation, a remote terminal, a mobile device, a user terminal, aterminal, a wireless communications device, a user agent, or a userapparatus. The terminal device in the embodiments of this applicationmay be a mobile phone, a tablet computer, a computer having a wirelesssending and receiving function, a virtual reality (VR) terminal device,an augmented reality (AR) terminal device, a wireless terminal inindustrial control, a wireless terminal in self driving, a wirelessterminal in telemedicine (remote medical), a wireless terminal in asmart grid, a wireless terminal in transportation safety, a wirelessterminal in a smart city, a wireless terminal in a smart home, and thelike. An application scenario is not limited in the embodiments of thisapplication. In this application, the foregoing terminal devices andchips that can be disposed in the foregoing terminal devices arecollectively referred to as terminal devices.

In addition, the communications system 100 may be alternatively a publicland mobile network (PLMN), a device-to-device (D2D) network, amachine-to-machine (M2M) network, or another network.

It should be understood that, FIG. 1 shows one network device and aplurality of terminals as an example. The wireless communications system100 may include a plurality of network devices, and there may be anotherquantity of terminals in a coverage area of each network device. This isnot limited in the embodiments of this application.

For ease of understanding of the embodiments of this application, thefollowing first briefly describes several concepts in the embodiments ofthis application.

1. Resource element (RE): A resource element is a smallest resourceunit, may be corresponding to one symbol in time domain, and may becorresponding to one subcarrier in frequency domain.

2. Resource block (RB): One RB occupies N_(sc) ^(RB) consecutivesubcarriers in frequency domain, where N_(sc) ^(RB) is a positiveinteger. For example, N_(sc) ^(RB) is 12 in an LTE protocol. In theembodiments of this application, an RB may be defined only from aperspective of a frequency domain resource. In other words, a quantityof time domain resources occupied by an RB in time domain is notlimited.

3. Symbol: A symbol is a smallest unit of a time domain resource. A timelength of one symbol is not limited in the embodiments of thisapplication. A length of one symbol may vary depending on differentsubcarrier spacings. Symbols may include an uplink symbol and a downlinksymbol. As an example rather than a limitation, the uplink symbol may bereferred to as a single carrier frequency division multiple access(SC-FDMA) symbol or an orthogonal frequency division multiple (OFDM)access symbol, and the downlink symbol may be referred to as an OFDMsymbol.

4. Control channel: A control channel is a channel that can be used tocarry resource scheduling information and other control information. Forexample, the control channel may be a PDCCH or an enhanced physicaldownlink control channel (enhanced PDCCH, EPDCCH) defined in the LTEprotocol, may be a new radio physical downlink control channel (newradio PDCCH, NRPDCCH) or another downlink channel that has the foregoingfunction and that is defined with network evolution, or may be an uplinkcontrol channel, such as a physical uplink control channel (PUCCH). Forease of description, a control channel transmission method in anembodiment of this application is described below in detail by using thephysical downlink control channel as an example. It should be understoodthat, the physical downlink control channel may be understood as ageneral term of downlink control channels, and may include but is notlimited to the downlink control channels listed above. It should befurther understood that, a channel may also be referred to as a signalor another name. This is not specifically limited in the embodiments ofthe present application.

Specifically, the physical downlink control channel in the embodimentsof this application may be alternatively a physical downlink controlchannel based on a cell-specific reference signal (CRS), or a physicaldownlink control channel based on a demodulation reference signal(DMRS). The CRS-based physical downlink control channel may be aphysical downlink control channel demodulated based on a CRS, and theDMRS-based physical downlink control channel may be a physical downlinkcontrol channel demodulated based on a DMRS. The CRS is a referencesignal (RS) configured by a network device for all terminal devices in acell. The DMRS is an RS configured by a network device for a specificterminal device, or may be referred to as a UE-specific reference signal(URS).

It should be noted that, a physical downlink control channel defined inan NR system may be the DMRS-based physical downlink control channel.

5. Aggregation level (AL): An aggregation level may indicate a quantityof consecutive control channel elements (CCEs) occupied by one physicaldownlink control channel. To be specific, an aggregation level of aphysical downlink control channel is L if the downlink control channelis formed by aggregating L CCEs, or in other words, the downlink controlchannel can be transmitted on L consecutive CCEs, where L is a positiveinteger. Specifically, a value of L may be 1, 2, 4, or 8, or may furtherbe 16 or 32. A value of the aggregation level is not specificallylimited in the embodiments of the present application.

6. Resource element group (REG) and control channel element (CCE): Aresource element group and a control channel element are basic units forphysical-resource allocation for downlink control signaling, and areused to define a mapping from the downlink control signaling to an RE.For example, it is specified in the LTE protocol that, one CCE includesnine REGs, and one REG includes four non-reference signal (referencesignal, RS) REs that are consecutive in frequency domain. In otherwords, one CCE includes 36 REs. It should be understood that, the REGand the CCE are merely units used for resource allocation, and shall notconstitute any limitation on this application. This application does notexclude a possibility of defining a new resource allocation unit in afuture protocol to implement a same or similar function.

7. Search space: A search space is used as a search range of blinddetection of a terminal device. The concept of search space is definedin an existing protocol (for example, the LTE protocol). The searchspace is a set of candidate downlink control channels that need to bemonitored by the terminal device. The search space may include a commonsearch space and a UE-specific search space. The common search space isused to transmit cell-level common information, which may include, forexample, control information related to paging, a random access response(RAR), and a broadcast control channel (BCCH). The UE-specific searchspace is used to transmit terminal device (or UE)-level information,which may include, for example, control information related to adownlink shared channel (DL-SCH) and an uplink shared channel (UL-SCH).

8. Control resource set (CORESET): A control resource set is a set ofresources used to transmit downlink control information, and may also bereferred to as a control resource area or a physical downlink controlchannel resource set.

A control channel may be divided into a plurality of control resourcesets, and each control resource set is a set of REGs. The terminaldevice may monitor a physical downlink control channel on one or morecontrol resource sets.

For the network device, the control resource set may be understood as aset of resources that may be occupied for sending a control channel. Forthe terminal device, search spaces of physical downlink control channelsof all terminal devices belong to the control resource set. In otherwords, the network device may determine, from the control resource set,a resource used for sending a physical downlink control channel, and theterminal device may determine a search space of a physical downlinkcontrol channel from the control resource set. The control resource setmay include time-frequency resources, for example, may be a segment ofbandwidth or one or more subbands in frequency domain, and may be one ormore time units in time domain. One CORESET may be consecutive ornon-consecutive resource units in time domain or frequency domain, forexample, consecutive resource blocks (RBs) or non-consecutive RBs.

It should be understood that, the CORESET described above is an exampleof the control resource set, and shall not constitute any limitation onthis application. This application does not exclude a possibility ofreplacing the CORESET with another name in a future protocol toimplement a same or similar function.

It should be further understood that, specific content of the frequencydomain resource, the time domain resource, and the time-frequencyresource illustrated above is merely used for example description, andshall not constitute any limitation on the embodiments of the presentapplication. For example, the RB is an example of the resource unit. Asize of the RB may be defined in an existing LTE protocol or may bedefined in a future protocol, or the RB may be replaced with anothername. For another example, a time unit may be a subframe, may be a slot(slot), may be a radio frame, a mini-slot (or sub-slot), a plurality ofaggregated slots, a plurality of aggregated subframes, or a symbol, ormay even be a transmission time interval (TTI). This is not specificallylimited in the embodiments of this application.

The following describes the embodiments of this application in detailwith reference to the accompanying drawings.

It should be understood that, the technical solutions of thisapplication may be applied to a wireless communications system, forexample, the communications system 100 shown in FIG. 1. Thecommunications system may include at least one network device and atleast one terminal device. The network device may communicate with theterminal device through a wireless air interface. For example, thenetwork device in the communications system may be corresponding to thenetwork device 102 shown in FIG. 1, and the terminal device in thecommunications system may be corresponding to the terminal devices 104to 114 shown in FIG. 1.

Without loss of generality, the following describes the embodiments ofthis application in detail by using an interaction process between oneterminal device and a network device as an example. The terminal devicemay be any terminal device that is in the wireless communications systemand that has a wireless connection relationship with the network device.It can be understood that, the network device and a plurality ofterminal devices that are in the wireless communications system and thathave a wireless connection relationship may perform transmission ofreference signals according to the same technical solutions. This is notlimited in this application.

FIG. 2 is a schematic flowchart of a communication method 200 accordingto an embodiment of this application from the perspective of deviceinteraction. As shown in FIG. 2, the method 200 includes step 210 tostep 240.

Step 210: A terminal device determines a maximum number of blinddetection in a first time unit.

The maximum number of blind detection may be used to indicate a maximumnumber of blind detection that the terminal device is capable ofperforming in the first time unit. Alternatively, the first time unit iscorresponding to the maximum number of blind detection, and in step 210,the terminal device determines the maximum number of blind detectionthat is corresponding to the first time unit. Herein, the first timeunit may be a predefined (for example, protocol-defined) time length.The first time unit may include one or more symbols. For example, thefirst time unit may be one slot, or the first time unit may be k (k is apositive integer) symbols, and a time length of the k symbols is lessthan one slot. If a slot definition in an LTE protocol is still used, kis, for example, less than 14 with a normal cyclic prefix. Optionally,the maximum number of blind detection may be predefined.

For example, the maximum number of blind detection may be defined in aprotocol. The maximum number of blind detection of the terminal devicemay be fixed in the protocol, or different maximum numbers of blinddetection are defined based on different service types. This is notlimited in this application.

Optionally, the maximum number of blind detection may be reported by auser equipment.

For example, the user equipment reports, to a network device based on acapability of the user equipment, the maximum number of blind detectionperformed in the first time unit.

Optionally, the maximum number of blind detection is indicated by thenetwork device.

In this case, the method 200 further includes step 2101: The terminaldevice receives first indication information sent by the network device,where the first indication information is used to indicate the maximumnumber of blind detection.

Correspondingly, in step 2101, the network device sends the firstindication information, where the first indication information is usedto indicate the maximum number of blind detection.

Specifically, the maximum number of blind detection of the terminaldevice may be determined based on a control resource usage status and acapability of the terminal device. In a possible implementation, theterminal device may report, to the network device, an initial maximumnumber of blind detection (for ease of differentiation, a maximum numberof blind detection that is corresponding to the capability of theterminal device is referred to as the initial maximum number of blinddetection) that can represent the capability of the terminal device, andthe network device may determine the maximum number of blind detectionof the terminal device based on the initial maximum number of blinddetection of the terminal device, a network resource usage status, andthe like, and indicate the maximum number of blind detection to theterminal device by using signaling.

Optionally, the method 200 further includes: reporting, by the terminaldevice, the initial maximum number of blind detection performed in thefirst time unit. Alternatively, the terminal device reports the initialmaximum number of blind detection that is corresponding to the firsttime unit.

For example, the terminal device may report, to the network device basedon the capability of the terminal device, the initial maximum number ofblind detection performed in the first time unit. The initial maximumnumber of blind detection may be greater than or equal to the maximumnumber of blind detection.

Step 220: The network device sends at least one physical downlinkcontrol channel in the first time unit.

Specifically, the network device may send one or more physical downlinkcontrol channels to a same terminal device in the first time unit. Inother words, the network device may send downlink control information(DCI) in one or more formats to a same terminal device in the first timeunit. For different formats of downlink control information, blinddetection periods of corresponding physical downlink control channelsare different. For example, a blind detection period of a physicaldownlink control channel 1 may be one slot, and a blind detection periodof a physical downlink control channel 2 may be three symbols.Therefore, for downlink control information in different formats, blinddetection periods included in a same first time unit are different.Further, a blind detection period of downlink control information ineach format may be configured for the terminal device by using higherlayer signaling.

FIG. 3 is a schematic diagram of a blind detection period. FIG. 3 is aschematic diagram of sending physical downlink control channels in twodownlink control information formats on a control resource set (forexample, a CORESET). A blind detection period of a physical downlinkcontrol channel 1 may be one slot, and a blind detection period of aphysical downlink control channel 2 may be m (m≥1, and m is an integer)symbols, for example, m=3.

It should be noted that, resources in the control resource set may bedefined according to a protocol. In other words, resource locations inthe control resource set may be pre-determined and fixed. If the networkdevice is willing to send a physical downlink control channel, thenetwork device first selects a control resource set, and sends thephysical downlink control channel on the selected control resource set.

Actually, two slots shown in FIG. 3 overlap in time domain. The twoslots corresponding to the two physical downlink control channels areseparately drawn in the figure only for ease of description andunderstanding. The two physical downlink control channels may be sent ondifferent control resource sets. In other words, in two figures in anupper part of FIG. 3, there are two control resource sets in the firstleftmost column, the physical downlink control channel 1 may be sent onthe first control resource set, the physical downlink control channel 2is sent on the second control resource set, wherein the first controlresource set and the second control resource set are in an order fromthe top down in FIG. 3, and only the physical downlink control channel 2may be sent on three remaining control resource sets. Similarly, the twophysical downlink control channels may be sent on a same controlresource set. If the two slots corresponding to the physical downlinkcontrol channel 1 and the physical downlink control channel 2 are drawnin an overlapping manner, a figure shown on the bottom of FIG. 3 can beobtained. In other words, the physical downlink control channel 1 andthe physical downlink control channel 2 may be sent on the firstleftmost control resource set, and only the physical downlink controlchannel 2 may be sent on the three remaining control resource sets.

In this embodiment of this application, two or more blind detectionperiods that overlap in time domain may be referred to as one blinddetection occasion (blind detection occasion). Therefore, if a firsttime unit shown in FIG. 3 is one slot, the first time unit may includefour blind detection occasions.

In other words, the first time unit includes N (N is a positive integer,and N≥2) blind detection occasions, and the N blind detection occasionsmay be determined based on a blind detection period of each of aplurality of physical downlink control channels. In other words, thefirst time unit is corresponding to the N blind detection occasions,where N is a positive integer, and N≥2.

The terminal device may perform physical downlink control channel blinddetection successively on corresponding control resource sets in all theblind detection occasions based on a chronological order of theplurality of blind detection occasions.

It should be noted that the control resource set is a set of resourcesused to carry a physical downlink control channel. In this embodiment ofthis application, the control resource set may be periodic only in aslot, but does not span a boundary of the slot. A plurality of controlresource sets may be periodically configured in one slot, and theplurality of control resource sets may have same duration and sameperiods. However, CORESETs configured in any two slots may havedifferent start locations and different periods, or may have same startlocations and same periods.

For ease of understanding, FIG. 4 to FIG. 6 are schematic diagrams ofcontrol resource set configurations.

As shown in FIG. 4, in 14 symbols included in each slot (for example, aslot 1 and a slot 2), a start location of a control resource set is thezeroth symbol in the slot, duration of the control resource set is threesymbols, and one control resource set period is five symbols. In otherwords, control resource sets occur at intervals of two symbols. 14symbols cannot be equally allocated to control resource set periods,each of which includes five symbols. Therefore, an interval between thelast control resource set in the slot 1 and the first control resourceset in the slot 2 is not necessarily equal to an interval between twocontrol resource sets in one slot.

As shown in FIG. 5, in the first slot (namely, a slot 1), a startlocation of a control resource set is the first symbol in the slot,duration of the control resource set is two symbols, and one controlresource set period is four symbols. In other words, control resourcesets occur at intervals of two symbols. There are three remainingsymbols after the last control resource set in a current slot (forexample, the slot 1), and the three remaining symbols are not enough forone control resource set period. Therefore, no control resource set isconfigured on the three symbols. In a next slot (namely, a slot 2),control resource set configuration still starts from the first symbol.In other words, a start location of a control resource set is the samerelative to a location of a start boundary of the slot.

It can be learned from FIG. 4 and FIG. 5 that, control resource sets areperiodically distributed in one slot, and control resource sets in anytwo slots have same start locations and same duration.

As shown in FIG. 6, in the first slot (namely, a slot 1), a startlocation of a control resource set is the first symbol in the slot,duration of the control resource set is two symbols, and one controlresource set period is four symbols. In other words, control resourcesets occur at intervals of two symbols. There are three remainingsymbols after the last control resource set in a current slot (forexample, the slot 1), and the three remaining symbols are not enough forone control resource set period. Therefore, a one-symbol controlresource set is configured on the last symbol of the three symbols, toensure that the control resource set does not span a boundary of theslot. In other words, one CORESET does not span two slots. In a nextslot (namely, a slot 2), control resource set configuration still startsfrom the first symbol. In other words, a start location of a controlresource set is the same relative to a location of a start boundary ofthe slot.

When a plurality of control resource sets are configured in a pluralityof slots, alternatively, start locations and duration of the controlresource sets in the slots may be separately configured. For example, ina slot group 1 including at least one slot, control resource sets in theslot have same start locations and same duration, and in a slot group 2including at least one slot, control resource sets in the slot also havesame start locations and same duration, but a start location andduration of a control resource set in any slot in the slot group 1 aredifferent from a start location and duration of a control resource setin any slot in the slot group 2. In other words, control resource setsare periodically distributed in one slot, and control resource sets inat least two slots have different start locations and/or differentduration.

For ease of understanding, FIG. 7 is yet another schematic diagram of acontrol resource set configuration. As shown in FIG. 7, a start locationof a control resource set in each of a slot 1 and a slot 2 is the zerothsymbol in the slot, a control resource set period is five symbols, andduration of the control resource set is three symbols; a start locationof a control resource set in each of a slot 3 and a slot 4 is the firstsymbol in the slot, a control resource set period is four symbols, andduration of the control resource set is two symbols. Therefore, the slot1 and the slot 2 constitute one slot group, and the slot 3 and the slot4 constitute another slot group.

Optionally, the method 200 further includes step 230: The network devicesends configuration information, where the configuration information isused to indicate a number of blind detection in each blind detectionoccasion.

Specifically, the configuration information may include at least one ofthe following: at least one downlink control information (DCI) format ineach blind detection occasion, an aggregation level corresponding toeach DCI format, a quantity of a plurality of candidate physicaldownlink control channels at a same aggregation level, a quantity N ofthe blind detection occasions in the first time unit, and the totalnumber of blind detection in each blind detection occasion.

Correspondingly, in step 230, the terminal device receives theconfiguration information, where the configuration information is usedto determine the number of blind detection in each blind detectionoccasion.

It should be noted that, downlink control information in differentformats may occupy different quantities of CCEs, namely, may becorresponding to different aggregation levels. Further, each downlinkcontrol information format may be corresponding to at least oneaggregation level. The network device may configure a quantity ofcandidate physical downlink control channels for each aggregation level.A set of candidate physical downlink control channels constitute asearch space.

In a possible design, the terminal device may determine, based on theconfiguration information, the number, configured by the network devicefor the terminal device, of blind detection in each blind detectionoccasion. In this way, the terminal device can determine a format ofdownlink control information to be blindly detected and a blinddetection occasion in which the downlink control information is to beblindly detected.

In another possible design, the terminal device may determine the numberof blind detection in each blind detection occasion based on the maximumnumber of blind detection and the quantity N of the blind detectionoccasions in the first time unit. To be specific, the maximum number ofblind detection is divided by the total quantity of the blind detectionoccasions. When the maximum number of blind detection is not divisibleby the total quantity of the blind detection occasions, rounding up,rounding down, or rounding off may be performed.

In still another possible design, the terminal device may obtain thenumber of blind detection in each blind detection occasion based on theconfiguration information. In other words, the configuration informationdirectly indicates the number of blind detection in each blind detectionoccasion.

In this embodiment of this application, numbers, configured by thenetwork device for the terminal device, of blind detection in all blinddetection occasions may be equal or unequal.

Still using FIG. 3 as an example, the first time unit includes fourblind detection occasions, and the network device may configure aquantity of candidate physical downlink control channels for eachaggregation level corresponding to each downlink control informationformat.

For example, aggregation levels corresponding to a downlink controlinformation format of the physical downlink control channel 1 in FIG. 3are aggregation levels 1 and 2, and there are six candidate physicaldownlink control channels at each of the aggregation levels 1 and 2;aggregation levels corresponding to a downlink control informationformat of the physical downlink control channel 2 are aggregation levels4 and 8, and there are eight candidate physical downlink controlchannels at the aggregation level 4, and six candidate physical downlinkcontrol channels at the aggregation level 8.

In other words, equal allocation may be understood as that quantities,configured by the network device for one aggregation level of onedownlink control information format, of candidate physical downlinkcontrol channels in any two blind detection occasions are the same.However, this does not indicate that actual number of blind detectionperformed by the terminal device in any two blind detection occasionsfor one aggregation level of one downlink control information format arethe same.

In a case of equal allocation, the network device may indicate, in theconfiguration information, a quantity, configured for each blinddetection occasion, of candidate physical downlink control channels ateach aggregation level corresponding to each downlink controlinformation format; or the network device may indicate, in theconfiguration information, a quantity of candidate physical downlinkcontrol channels at each aggregation level corresponding to eachdownlink control information format, and indicate, by using othersignaling, that numbers of blind detection in the plurality of blinddetection occasions are equally allocated. This is not limited in thisapplication.

For another example, the network device may perform the followingconfiguration: In the first blind detection occasion, a quantity ofcandidate physical downlink control channels for the physical downlinkcontrol channel 1 at the aggregation level 1 is 6, a quantity ofcandidate physical downlink control channels for the physical downlinkcontrol channel 1 at the aggregation level 2 is 6, a quantity ofcandidate physical downlink control channels for the physical downlinkcontrol channel 2 at the aggregation level 4 is 1, and a quantity ofcandidate physical downlink control channels for the physical downlinkcontrol channel 2 at the aggregation level 8 is 1; and in threeremaining blind detection occasions, a quantity of candidate physicaldownlink control channels for the physical downlink control channel 2 atthe aggregation level 4 is 8, and a quantity of candidate physicaldownlink control channels for the physical downlink control channel 2 atthe aggregation level 8 is 6.

In other words, unequal allocation may be understood as that quantities,configured by the network device for one aggregation level of onedownlink control information format (for example, the physical downlinkcontrol channel 2), of candidate physical downlink control channels inat least two blind detection occasions are different.

In a case of unequal allocation, the network device may indicate, in theconfiguration information, a quantity, configured for each blinddetection occasion, of candidate physical downlink control channels ateach aggregation level corresponding to each downlink controlinformation format.

In this embodiment of this application, the physical downlink controlchannel blind detection configuration information may be indicated byusing higher layer signaling (for example, a radio resource control(RRC) message).

Optionally, step 230 specifically includes:

sending, by the network device, the RRC message, where the RRC messagecarries the physical downlink control channel blind detectionconfiguration information.

It should be understood that, the physical downlink control channelblind detection configuration information carrying in the RRC message isonly a possible implementation.

Step 240: The terminal device performs physical downlink control channelblind detection in the i^(th) (i is a positive integer, and i≤N) blinddetection occasion.

Specifically, the terminal device may perform physical downlink controlchannel blind detection in a blind detection occasion of each physicaldownlink control channel based on the PDCCH blind detectionconfiguration information that is obtained in advance (for example,received from the network device in step 230).

In this embodiment of this application, the network device may send theat least one physical downlink control channel in the N blind detectionoccasions according to a preset rule based on one or more items of thefirst information listed above. The terminal device may perform physicaldownlink control channel blind detection in each blind detectionoccasion according to the preset rule based on one or more items of thefirst information listed above.

As an example rather than a limitation, in step 220, the network devicemay send the at least one physical downlink control channel according toany one of or a combination of more than one of the following rules:

Rule 1: When a plurality of control resource sets are distributed in thei^(th) blind detection occasion, an available control resource set isselected from the plurality of control resource sets based on adescending order of priorities of the plurality of control resourcesets, and the at least one physical downlink control channel is sent byusing the available control resource set.

For example, if a plurality of control resource sets are distributed inthe i^(th) blind detection occasion, the network device may select anavailable control resource set based on a descending order of prioritiesof the plurality of control resource sets, and send the one or morephysical downlink control channels by using the available controlresource set.

Rule 2: An available search space is selected from a plurality of searchspaces in the i^(th) blind detection occasion based on a priority orderof search space types, and the at least one physical downlink controlchannel is sent by using the available search space.

For example, the search spaces include a common search space and auser-specific search space. If a priority of the common search space ishigher than a priority of the user-specific search space, the one ormore physical downlink control channels are sent by using the commonsearch space firstly and then using the user-specific search space.Therefore, if the network device sends the one or more physical downlinkcontrol channels in the i^(th) blind detection occasion, the one or morephysical downlink control channels are preferentially sent by using thecommon search space.

Rule 3: When there are a plurality of downlink control informationformats, the at least one physical downlink control channel is sent inthe i^(th) blind detection occasion based on a priority order of thedownlink control information formats.

For example, if the network device sends physical downlink controlchannels in a plurality of downlink control information formats to asame terminal device, and the physical downlink control channels in theplurality of downlink control information formats are configured in thei^(th) blind detection occasion, one or more physical downlink controlchannels may be sent in the i^(th) blind detection occasion based on apriority order of the downlink control information formats.

Rule 4: A same downlink control information format is corresponding to aplurality of aggregation levels, and physical downlink control channeltransmission is performed in the i^(th) blind detection occasion basedon a descending order or an ascending order of the aggregation levels.

For example, if a format of downlink control information sent by thenetwork device in the i^(th) blind detection occasion is correspondingto a plurality of aggregation levels, at least one available aggregationlevel may be selected based on a descending order of the aggregationlevels, and the one or more physical downlink control channels are sentby using the at least one available aggregation level.

Rule 5: If there are a plurality of candidate physical downlink controlchannels at a same aggregation level, the at least one physical downlinkcontrol channel is sent in the i^(th) blind detection occasion based ona descending order or an ascending order of serial numbers of startcontrol channel elements (for example, CCE) of the plurality ofcandidate physical downlink control channels at the same aggregationlevel.

For example, if there are a plurality of candidate physical downlinkcontrol channels at a same aggregation level, the network device mayselect an available control channel element based on a descending orderof serial numbers of start control channel elements of the plurality ofcandidate physical downlink control channels at the same aggregationlevel, and send the one or more physical downlink control channels byusing the available control channel element.

The foregoing rules may be used in combination. Specific rules accordingto which the network device sends the physical downlink control channelare predefined, or specified in a protocol, or may be selected by thenetwork device and notified to the terminal device by using signaling.

Correspondingly, in step 240, the terminal device may perform blinddetection according to any one of or a combination of more than one ofthe following rules:

Rule 1: When a plurality of control resource sets are distributed in thei^(th) blind detection occasion, physical downlink control channel blinddetection is performed successively on the plurality of control resourcesets based on a descending order of priorities of the plurality ofcontrol resource sets.

Rule 2: Physical downlink control channel blind detection is performedsuccessively in a plurality of search spaces based on a priority orderof search space types in the i^(th) blind detection occasion.

For example, the search spaces include a common search space and auser-specific search space. If a priority of the common search space ishigher than a priority of the user-specific search space, physicaldownlink control channel blind detection is performed successively inthe plurality of search spaces in the i^(th) blind detection occasionbased on an order of first the common search space and then theuser-specific search space.

Rule 3: When there are a plurality of downlink control informationformats, physical downlink control channel blind detection is performedin the i^(th) blind detection occasion based on a priority order of thedownlink control information formats.

For example, if the network device sends physical downlink controlchannels in a plurality of downlink control information formats to asame terminal device, and the physical downlink control channels in theplurality of downlink control information formats are configured in thei^(th) blind detection occasion, the physical downlink control channelsin the plurality of downlink control information formats may be blindlydetected successively based on a priority order of the downlink controlinformation formats.

Rule 4: A same downlink control information format is corresponding to aplurality of aggregation levels, and physical downlink control channelblind detection is performed in the i^(th) blind detection occasionbased on a descending order or an ascending order of the aggregationlevels.

Rule 5: If there are a plurality of candidate physical downlink controlchannels at a same aggregation level, physical downlink control channelblind detection is performed in the i^(th) blind detection occasionbased on a descending order or an ascending order of start CCE numbersof the plurality of candidate physical downlink control channels at thesame aggregation level.

The foregoing rules may be used in combination. Specific rules accordingto which the terminal device performs physical downlink control channelblind detection are predefined, or specified in a protocol, or may beselected by the network device and notified to the terminal device byusing signaling.

For example, the rule 1 and the rule 2 are used in combination.

Physical downlink control channel blind detection is preferentiallyperformed on a control resource set (for example, a control resource set1) with a higher priority in a blind detection occasion, and thenphysical downlink control channel blind detection is performed on acontrol resource set (for example, a control resource set 2) with alower priority.

When the control resource set 1 includes a common search space and auser-specific search space, based on a priority order of the commonsearch space and the user-specific search space, physical downlinkcontrol channel blind detection may be preferentially performed in asearch space (for example, the user-specific search space) with a higherpriority, and then physical downlink control channel blind detection isperformed in a search space (for example, the common search space) witha lower priority.

A specific process of performing blind detection on the control resourceset 2 is similar to a specific process of performing blind detection onthe control resource set 1. For brevity, details are not describedherein again.

For another example, the rule 3 and the rule 4 are used in combination.

When there are a plurality of downlink control information formats, forexample, a downlink control information format A and a downlink controlinformation format B, based on a priority order of the downlink controlinformation formats, detection is first performed for a downlink controlinformation format (for example, the downlink control information formatA) with a higher priority, and then detection is performed for adownlink control information format (for example, the downlink controlinformation format B) with a lower priority. Blind detection for thedownlink control information format A is performed based on anaggregation level corresponding to the downlink control informationformat and a corresponding quantity of candidate physical downlinkcontrol channels.

If the downlink control information format A is corresponding to twoaggregation levels, for example, an aggregation level 2 and anaggregation level 4, blind detection is performed based on a descendingorder of the aggregation levels. Therefore, blind detection ispreferentially performed on a plurality of candidate physical downlinkcontrol channels at the aggregation level 4, and then blind detection isperformed on a plurality of candidate physical downlink control channelsat the aggregation level 2.

A specific process of detection for the downlink control informationformat B is similar to a specific process of detection for the downlinkcontrol information format A. For brevity, details are not describedherein again.

For still another example, the rule 4 and the rule 5 are used incombination.

If a same downlink control information format is corresponding to atleast two aggregation levels, for example, an aggregation level 4 and anaggregation level 8, blind detection is performed based on an ascendingorder of the aggregation levels. Therefore, blind detection ispreferentially performed on a plurality of candidate physical downlinkcontrol channels at the aggregation level 4, and then blind detection isperformed on a plurality of candidate physical downlink control channelsat the aggregation level 8.

During blind detection on the plurality of candidate physical downlinkcontrol channels at the aggregation level 4, locations of the pluralityof candidate physical downlink control channels may be first determined,namely, a serial number of a start CCE of each candidate physicaldownlink control channel is calculated; and then blind detection isperformed successively on the plurality of candidate physical downlinkcontrol channels at the aggregation level 4 based on a descending orderor an ascending order of serials number of the start CCEs of theplurality of candidate physical downlink control channels.

A specific process of performing blind detection on the plurality ofcandidate physical downlink control channels at the aggregation level 8is similar to a specific process of performing blind detection on theplurality of candidate physical downlink control channels at theaggregation level 4. For brevity, details are not described hereinagain.

A plurality of blind detection rules and combinations of the pluralityof rules are illustrated above, but this shall not constitute anylimitation on this application. Physical downlink control channel blinddetection performed by using any one of the foregoing rules shall fallwithin the protection scope claimed by this application.

The following describes, in detail with reference to specific examples,blind detection rules provided in this embodiment of this application.

In the following embodiments, it is assumed that the maximum number ofblind detection in the first time unit is 44.

Embodiment 1

The physical downlink control channel 1 shown in FIG. 3 is used as anexample. It is assumed that the network device sends only one physicaldownlink control channel, namely, the physical downlink control channel1, in the first time unit. As described above, two aggregation levels,AL=1 and AL=2, are configured for the physical downlink control channel1. It is assumed that a quantity of candidate physical downlink controlchannels corresponding to each of the two aggregation levels is 6.Therefore, the terminal device may successively perform physicaldownlink control channel blind detection based on an ascending order ora descending order of the aggregation levels according to the rule 4.

Because a number of blind detection of the terminal device in the blinddetection occasion is 12, which does not reach the maximum number 44 ofblind detection, blind detection is not limited by the maximum number ofblind detection.

Embodiment 2

The physical downlink control channel 1 and the physical downlinkcontrol channel 2 shown in FIG. 3 are still used as an example. It isassumed that the network device sends two physical downlink controlchannels, namely, the physical downlink control channel 1 and thephysical downlink control channel 2, in the first time unit. Physicaldownlink control channels in two downlink control information formatsare configured for the first blind detection occasion, and a physicaldownlink control channel in only one downlink control information formatis configured for the second to the fourth blind detection occasions.Therefore, the terminal device may perform physical downlink controlchannel blind detection in the first blind detection occasion based onthe two downlink control information formats, and the terminal devicemay perform physical downlink control channel blind detection in thesecond to the fourth blind detection occasions based on the one downlinkcontrol information format.

It is assumed that numbers, configured by the network device for theterminal device, of blind detection in all blind detection occasions areequal. As described above, two aggregation levels, AL=1 and AL=2, areconfigured for the physical downlink control channel 1, andcorresponding quantities of candidate physical downlink control channelsare 6; and two aggregation levels, AL=4 and AL=8, are configured for thephysical downlink control channel 2. It is assumed that a quantity ofcandidate physical downlink control channels at the aggregation level 4is 8, and a quantity of candidate physical downlink control channels atthe aggregation level 8 is 6.

In the first blind detection occasion, according to the rule 3 and therule 4, the terminal device may first determine a downlink controlinformation format for which blind detection is preferentiallyperformed, and then perform blind detection based on aggregation levelscorresponding to the downlink control information format for which blinddetection is preferentially performed and a corresponding quantity ofcandidate physical downlink control channels. Assuming that the downlinkcontrol information format for which blind detection is preferentiallyperformed is the physical downlink control channel 1, the terminaldevice first performs blind detection in the first blind detectionoccasion based on the aggregation level 1 and the aggregation level 2.Further, the terminal device may perform physical downlink controlchannel blind detection based on a priority order of the aggregationlevels, for example, based on an ascending order of the aggregationlevels. Therefore, preferentially based on the aggregation level 1,blind detection is performed on the six candidate physical downlinkcontrol channels at the aggregation level 1; and then based on theaggregation level 2, blind detection is performed on the six candidatephysical downlink control channels at the aggregation level 2. Then, theterminal device performs blind detection for a downlink controlinformation format of the physical downlink control channel 2. Theterminal device can still perform physical downlink control channelblind detection based on an ascending order of the aggregation levels.In this case, first based on the aggregation level 4, the terminaldevice performs blind detection on the eight candidate physical downlinkcontrol channels at the aggregation level 4; and then based on theaggregation level 8, the terminal device performs blind detection on thesix candidate physical downlink control channels at the aggregationlevel 8.

After detection in the first blind detection occasion, a number of blinddetection of the terminal device reaches 26. Then, the terminal deviceperforms physical downlink control channel blind detection in the secondblind detection occasion. Because no physical downlink control channel 1is configured in the second blind detection occasion, the terminaldevice needs to perform blind detection only on the physical downlinkcontrol channel 2. Therefore, blind detection can be directly performedon the eight candidate physical downlink control channels at theaggregation level 4 and the six candidate physical downlink controlchannels at the aggregation level 8.

After detection in the second blind detection occasion, a number ofblind detection of the terminal device reaches 40, and only four timesare left. Then, the terminal device performs physical downlink controlchannel blind detection in the third blind detection occasion. Becauseno physical downlink control channel 1 is configured in the third blinddetection occasion, the terminal device needs to perform blind detectiononly on the physical downlink control channel 2. Because only four timesof blind detection are left, blind detection cannot be performedseparately on the eight candidate physical downlink control channels atthe aggregation level 4 and the six candidate physical downlink controlchannels at the aggregation level 8. According to the rule describedabove, the terminal device performs physical downlink control channelblind detection based on an ascending order of the aggregation levels.Therefore, the terminal device preferentially performs blind detectionon four candidate physical downlink control channels at the aggregationlevel 4.

Further, the four candidate physical downlink control channels may beselected according to the preset rule 5. For example, blind detection isperformed on the first four candidate physical downlink control channelsbased on an ascending order of serial numbers of start control channelelements of the plurality of candidate physical downlink controlchannels.

It can be learned that, the rule 3, the rule 4, and the rule 5 are usedin combination in a process of physical downlink control channel blinddetection in Embodiment 2.

It should be understood that, in Embodiment 2, although the numbers,configured by the network device, of blind detection in all the blinddetection occasions are equal, numbers of blind detection performed bythe terminal device in any two blind detection occasions are notnecessarily the same. This is because blind detection is limited by themaximum number of blind detection. Therefore, whether the numbers,configured by the network device, of blind detection in the plurality ofblind detection occasions are equal does not necessarily determinewhether actual numbers of blind detection performed by the terminaldevice in the plurality of blind detection occasions are equal.

In other words, numbers of physical downlink control channel blinddetection in any two of the N blind detection occasions are the same; or

numbers of physical downlink control channel blind detection in at leasttwo of the N blind detection occasions are different.

Embodiment 3

The physical downlink control channel 1 and the physical downlinkcontrol channel 2 shown in FIG. 3 are still used as an example. It isassumed that the network device sends two physical downlink controlchannels, namely, the physical downlink control channel 1 and thephysical downlink control channel 2, in the first time unit. Physicaldownlink control channels in two downlink control information formatsare configured for the first blind detection occasion, and a physicaldownlink control channel in only one downlink control information formatis configured for the second to the fourth blind detection occasions.Therefore, the terminal device may perform physical downlink controlchannel blind detection in the first blind detection occasion based onthe two downlink control information formats, and the terminal devicemay perform physical downlink control channel blind detection in thesecond to the fourth blind detection occasions based on the one downlinkcontrol information format.

It is assumed that numbers, configured by the network device for theterminal device, of blind detection in all blind detection occasions areunequal. As described above, two aggregation levels, AL=1 and AL=2, areconfigured for the physical downlink control channel 1, andcorresponding quantities of candidate physical downlink control channelsare 6; and two aggregation levels, AL=4 and AL=8, are configured for thephysical downlink control channel 2. The network device may perform thefollowing configuration: A quantity of candidate physical downlinkcontrol channels corresponding to the first blind detection occasion orthe last blind detection occasion or any blind detection occasion is 1,and quantities of candidate physical downlink control channelscorresponding to other blind detection occasions are 5. Therefore, themaximum number 44 of blind detection is configured.

The terminal device may perform physical downlink control channel blinddetection successively in the blind detection occasions according torules illustrated above, such as the rule 3, the rule 4, and the rule 5illustrated in Embodiment 2, based on the numbers, configured by thenetwork device, of blind detection in all the blind detection occasions.

It should be understood that a specific process in which the terminaldevice performs physical downlink control channel blind detectionaccording to the rule 3, the rule 4, and the rule 5 is similar to aspecific process described in Embodiment 2. For brevity, detaileddescriptions on the specific process are omitted herein.

It should be noted that, an unequal allocation method is particularlyapplicable to a case in which a maximum number X of blind detection isnot divisible by the quantity N of the blind detection occasions, and acase in which a total quantity of candidate physical downlink controlchannels configured by the network device for the N blind detectionoccasions exceeds the maximum number X of blind detection.

It should be further understood that performing blind detection based onthe ascending order of the aggregation levels, the ascending order ofserial numbers of the start CCEs of the plurality of candidate physicaldownlink control channels, and the priorities of the downlink controlinformation formats illustrated above with reference to Embodiments 1,2, and 3 is merely used for example description, and shall notconstitute any limitation on this application. For example, the terminaldevice may alternatively perform physical downlink control channel blinddetection based on a descending order of the aggregation levels or adescending order of serial numbers of the start CCEs of the plurality ofcandidate physical downlink control channels. Priorities of the factorsillustrated above are not specifically limited in this application.

It should be noted that, priorities of the factors in the firstinformation illustrated above may be defined in a protocol, or may beindicated by the network device. This is not limited in thisapplication.

It can be learned from the foregoing embodiments that, when the networkdevice sends a plurality of physical downlink control channels to theterminal device, the terminal device does not need to perform blinddetection separately based on different scheduling periods. The networkdevice may select, according to one or more of the rules illustratedabove, a resource used for sending a physical downlink control channel,and the terminal device may perform blind detection simultaneously on aplurality of different physical downlink control channels according tothe one or more of the rules illustrated above, thereby preventing adetection omission of the terminal device. Further, a number of blinddetection of the terminal device is limited by defining the maximumnumber of blind detection in the first time unit, thereby reducing blinddetection complexity of the terminal device, and helping to reduceenergy consumption caused by blind detection.

The foregoing describes in detail the communication method provided inthe embodiments of this application, by using an example in which oneslot is the first time unit. Actually, the first time unit is notlimited to one slot, and may be alternatively a time length less thanone slot, for example, k symbols. In this case, the first time unit doesnot necessarily include a plurality of blind detection occasions. Inother words, the first time unit may include only one or even less thanone blind detection occasion.

For example, the first time unit is three symbols, and one blinddetection occasion is three symbols. In this case, the first time unitexactly includes one blind detection occasion. Alternatively, the firsttime unit is three symbols, and one blind detection occasion is fivesymbols. In this case, the first time unit includes less than one blinddetection occasion.

In this case, the terminal device may determine a maximum number ofblind detection in one blind detection occasion based on the maximumnumber of blind detection in the first time unit. For example, themaximum number of blind detection in the first time unit is X, the firsttime unit is k symbols, and one blind detection occasion includes d (dis a positive integer) symbols. Therefore, the maximum number of blinddetection in the blind detection occasion is: X/k*d. When X is notdivisible by k*d, rounding up, rounding down, or rounding off may beperformed for X/k*d. This is not limited in this application.

Embodiment 4

FIG. 8 is another schematic diagram of a blind detection period. FIG. 8is a schematic diagram of sending physical downlink control channels intwo downlink control information formats on a control resource set. Ascheduling period of a physical downlink control channel 1 may be oneslot, and a scheduling period of a physical downlink control channel 2may be three symbols. It is assumed that the first time unit is alsothree symbols, and the maximum number of blind detection in the firsttime unit is 16.

Therefore, the terminal device may determine that a maximum number ofblind detection in each blind detection occasion is 16/3*3=16.

It is assumed that physical downlink control channels in two downlinkcontrol information formats, namely, the physical downlink controlchannel 1 and the physical downlink control channel 2, are configuredfor the first blind detection occasion, and a physical downlink controlchannel in only one downlink control information format, namely, thephysical downlink control channel 2, is configured for the second to thefourth blind detection occasions. Therefore, the terminal device mayperform physical downlink control channel blind detection in the firstblind detection occasion based on the two downlink control informationformats, and the terminal device may perform physical downlink controlchannel blind detection in the second to the fourth blind detectionoccasions based on the one downlink control information format.

It is assumed that numbers, configured by the network device for theterminal device, of blind detection in all the blind detection occasionsare equal. As described above, two aggregation levels, AL=1 and AL=2,are configured for the physical downlink control channel 1, andcorresponding quantities of candidate physical downlink control channelsare 6; and two aggregation levels, AL=4 and AL=8, are configured for thephysical downlink control channel 2, a quantity of candidate physicaldownlink control channels corresponding to AL=4 is 8, and a quantity ofcandidate physical downlink control channels corresponding to AL=8 is 6.

According to the rule 3 and the rule 4, the terminal device may firstdetermine a downlink control information format for which blinddetection is preferentially performed, and then perform blind detectionbased on aggregation levels corresponding to the downlink controlinformation format for which blind detection is preferentially performedand a corresponding quantity of candidate physical downlink controlchannels. Assuming that the downlink control information format forwhich blind detection is preferentially performed is the physicaldownlink control channel 1, the terminal device first performs blinddetection in the first blind detection occasion based on the aggregationlevel 1 and the aggregation level 2. Further, the terminal device mayperform physical downlink control channel blind detection based on apriority order of the aggregation levels, for example, based on anascending order of the aggregation levels. Therefore, preferentiallybased on the aggregation level 1, blind detection is performed on thesix candidate physical downlink control channels at the aggregationlevel 1; and then based on the aggregation level 2, blind detection isperformed on the six candidate physical downlink control channels at theaggregation level 2. After blind detection on the physical downlinkcontrol channel 1, a number of blind detection of the terminal devicereaches 12, and only four times are left. Therefore, blind detectioncannot be performed for both the two aggregation levels of the physicaldownlink control channel 2.

The terminal device may perform, preferentially based on the aggregationlevel 4, blind detection on four candidate physical downlink controlchannels at the aggregation level 4 based on an ascending order of theaggregation levels according to the rule 4. The four candidate physicaldownlink control channels may be determined by the terminal deviceaccording to the rule 5.

A specific process in which the terminal device performs physicaldownlink control channel blind detection according to the rule 3, therule 4, and the rule 5 is similar to a specific process described in theforegoing content with reference to Embodiment 2. For brevity, detaileddescriptions on the specific process are omitted herein.

It should be understood that, the foregoing embodiment is described byassuming that the numbers, configured by the network device for theterminal device, of blind detection in all the blind detection occasionsare equal, but this shall not constitute any limitation on thisapplication.

It can be learned from the foregoing embodiment that, the first timeunit is not limited to one slot, and may be alternatively k symbols lessthan one slot. Even if the first time unit includes only one blinddetection occasion or a part of a blind detection occasion, the terminaldevice may deduce a maximum number of blind detection in one blinddetection occasion based on the maximum number of blind detection in thefirst time unit. In addition, a definition of the first time unit isrelatively flexible. Moreover, a number of blind detection of theterminal device in each blind detection occasion is limited, therebyreducing blind detection complexity of the terminal device, and helpingto reduce energy consumption caused by blind detection.

The foregoing describes, in detail with reference to FIG. 2 to FIG. 8,the communication method provided in the embodiments of thisapplication, and the following describes, in detail with reference toFIG. 9 to FIG. 12, a terminal device and a network device provided inembodiments of this application.

FIG. 9 is a schematic block diagram of a terminal device 500 accordingto an embodiment of this application. As shown in FIG. 9, the terminaldevice 500 includes a determining module 510 and a blind detectionmodule 520.

The determining module 510 is configured to determine a maximum numberof blind detection in a first time unit, where the first time unit isone or more symbols.

The blind detection module 520 is configured to perform physicaldownlink control channel blind detection in the i^(th) blind detectionoccasion, where the first time unit includes N blind detectionoccasions, and a number of physical downlink control channel blinddetection performed by the terminal device in the N blind detectionoccasions is less than or equal to the maximum number of blinddetection.

i and N are positive integers, i≤N, and N≥2.

Specifically, the terminal device 500 may be corresponding to theterminal device in the communication method 200 according to theembodiments of this application. The terminal device 500 may includemodules configured to perform the method performed by the terminaldevice in the communication method 200 in FIG. 2. In addition, themodules in the terminal device 500 and the foregoing other operationsand/or functions are separately used for implementing correspondingprocesses of the reference signal sending and receiving method 200 inFIG. 2. Specifically, the determining module 510 is configured toperform step 210 in the method 200, and the blind detection module 520is configured to perform step 240 in the method 200. A specific processin which the modules perform the foregoing corresponding steps has beendescribed in detail in the method 200. For brevity, details are notdescribed herein again.

FIG. 10 is a schematic structural diagram of a terminal device 600according to an embodiment of this application. The terminal device 600can perform all the methods in the foregoing embodiments. Therefore, forspecific details of the terminal device 600, refer to descriptions inthe foregoing embodiments. To avoid repetition, details are notdescribed herein again. The terminal device 600 shown in FIG. 10 mayinclude: a memory 610, a processor 620, an input/output interface 630,and a transceiver 640. The memory 610, the processor 620, theinput/output interface 630, and the transceiver 640 are connected toeach other through an inner connection path. The memory 610 isconfigured to store an instruction. The processor 620 is configured toexecute the instruction stored in the memory 620, to control theinput/output interface 630 to receive input data and information and tooutput data such as an operation result, and control the transceiver 640to send a signal.

The processor 620 is configured to determine a maximum number of blinddetection in a first time module, where the first time module is one ormore symbols.

The processor 620 is further configured to perform physical downlinkcontrol channel blind detection in the i^(th) blind detection occasion,where the first time module includes N blind detection occasions, and anumber of physical downlink control channel blind detection performed bythe terminal device in the N blind detection occasions is less than orequal to the maximum number of blind detection.

i and N are positive integers, i≤N, and N≥2.

Specifically, the terminal device 600 may be corresponding to theterminal device in the communication method 200 according to theembodiments of this application. The terminal device 600 may includemodules configured to perform the method performed by the terminaldevice in the communication method 200 in FIG. 2. In addition, themodules in the terminal device 600 and the foregoing other operationsand/or functions are separately used for implementing correspondingprocesses of the reference signal sending and receiving method 200 inFIG. 3. Specifically, the processor 620 is configured to perform step210 to step 240 in the method 200, and the transceiver 640 is configuredto perform step 2101 in the method 200. A specific process in which themodules perform the foregoing corresponding steps has been described indetail in the method 200. For brevity, details are not described hereinagain.

It should be understood that in this embodiment of this application, theprocessor 620 may be a general central processing unit (CPU), amicroprocessor, an application-specific integrated circuit (ASIC), orone or more integrated circuits, configured to execute a relatedprogram, to implement the technical solutions provided in theembodiments of this application.

It should be further understood that, the transceiver 640 is alsoreferred to as a communications interface, and is, for example but notlimited to, a transceiver-type transceiver apparatus, to implementcommunication between the terminal device 600 and another device or acommunications network.

The memory 610 may include a read-only memory and a random accessmemory, and provide an instruction and data to the processor 620. A partof the processor 620 may further include a non-volatile random accessmemory. For example, the processor 620 may further store informationabout a device type.

FIG. 11 is a schematic block diagram of a network device 700 accordingto an embodiment of this application. As shown in FIG. 11, the networkdevice 700 includes a sending module 710.

The sending module 710 is configured to send configuration information,where the configuration information is used to determine a number ofblind detection in each of N blind detection occasions in a first timeunit, where the first time unit includes the N blind detectionoccasions.

The sending module 710 is further configured to send at least onephysical downlink control channel in the i^(th) blind detection occasionof the N blind detection occasions, where the first time unit is one ormore symbols.

i and N are positive integers, i≤N, and N≥2.

Specifically, the network device 700 may be corresponding to the networkdevice in the communication method 200 according to the embodiments ofthis application. The network device 700 may include modules configuredto perform the method performed by the network device in thecommunication method 200 in FIG. 2. In addition, the modules in thenetwork device 700 and the foregoing other operations and/or functionsare separately used for implementing corresponding processes of thereference signal sending and receiving method 200 in FIG. 3.Specifically, the sending module 710 is configured to perform step 210,step 2101, step 220, and step 230 in the method 200. A specific processin which the modules perform the foregoing corresponding steps has beendescribed in detail in the method 200. For brevity, details are notdescribed herein again.

FIG. 12 is a schematic structural diagram of a network device 800according to an embodiment of this application. The network device 800shown in FIG. 12 may include: a memory 810, a processor 820, aninput/output interface 830, and a transceiver 840. The memory 810, theprocessor 820, the input/output interface 830, and the transceiver 840are connected to each other through an inner connection path. The memory810 is configured to store an instruction. The processor 820 isconfigured to execute the instruction stored in the memory 820, tocontrol the input/output interface 830 to receive input data andinformation and to output data such as an operation result, and controlthe transceiver 840 to send a signal.

The transceiver 840 is configured to send configuration information,where the configuration information is used to determine a number ofblind detection in each of N blind detection occasions in a first timeunit, where the first time unit includes the N blind detectionoccasions.

The transceiver 840 is further configured to send at least one physicaldownlink control channel in the i^(th) blind detection occasion of the Nblind detection occasions, where the first time unit is one or moresymbols.

i and N are positive integers, i≤N, and N≥2.

It should be understood that in this embodiment of this application, theprocessor 820 may be a general central processing unit (CPU), amicroprocessor, an application-specific integrated circuit (ASIC), orone or more integrated circuits, configured to execute a relatedprogram, to implement the technical solutions provided in theembodiments of this application.

It should be further understood that, the transceiver 840 is alsoreferred to as a communications interface, and is, for example but notlimited to, a transceiver-type transceiver apparatus, to implementcommunication between the network device 800 and another device or acommunications network.

The memory 810 may include a read-only memory and a random accessmemory, and provide an instruction and data to the processor 820. A partof the processor 820 may further include a non-volatile random accessmemory. For example, the processor 820 may further store informationabout a device type.

In an implementation process, steps in the foregoing method can beimplemented by using a hardware integrated logic circuit in theprocessor, or by using an instruction in a form of software. Thecommunication method disclosed with reference to the embodiments of thisapplication may be directly performed by a hardware processor, or may beperformed by using a combination of hardware in the processor and asoftware module. The software module may be located in a mature storagemedium in the art, such as a random access memory, a flash memory, aread-only memory, a programmable read-only memory, an electricallyerasable programmable memory, or a register. The storage medium islocated in the memory, and the processor reads information in the memoryand completes the steps in the foregoing method in combination with thehardware of the processor. To avoid repetition, details are notdescribed herein again.

It should be understood that, the processor in the embodiments of thisapplication may be a central processing unit (CPU), or may be anothergeneral purpose processor, a digital signal processor (DSP), anapplication-specific integrated circuit (ASIC), a field programmablegate array (FPGA) or another programmable logic device, a discrete gateor transistor logic device, a discrete hardware component, or the like.The general purpose processor may be a microprocessor, or the processormay be any conventional processor or the like.

It should be understood that, the processor in the embodiments of thisapplication may be a central processing unit (CPU), or may be anothergeneral purpose processor, a digital signal processor (DSP), anapplication-specific integrated circuit (ASIC), a field programmablegate array (FPGA) or another programmable logic device, a discrete gateor transistor logic device, a discrete hardware component, or the like.The general purpose processor may be a microprocessor, or the processormay be any conventional processor or the like.

It should be further understood that the memory in the embodiments ofthis application may be a volatile memory or a nonvolatile memory, ormay include both a volatile memory and a nonvolatile memory. Thenonvolatile memory may be a read-only memory (ROM), a programmableread-only memory (PROM), an erasable programmable read-only memory(EPROM), an electrically erasable programmable read-only memory(EEPROM), or a flash memory. The volatile memory may be a random accessmemory (RAM), used as an external cache. By way of example but notlimitative description, many forms of random access RAMs may be used,for example, a static random access memory (SRAM), a dynamic randomaccess memory (DRAM), a synchronous dynamic random access memory(SDRAM), a double data rate synchronous dynamic random access memory(DDR SDRAM), an enhanced synchronous dynamic random access memory(ESDRAM), a synchlink dynamic random access memory (SLDRAM), and adirect rambus random access memory (DR RAM).

All or some of the foregoing embodiments may be implemented by usingsoftware, hardware, firmware, or any combination thereof. When softwareis used for implementation, the foregoing embodiments may be implementedcompletely or partially in a form of a computer program product. Thecomputer program product includes one or more computer instructions.When the computer program instructions are loaded and executed on acomputer, the procedures or functions according to the embodiments ofthis application are all or partially generated. The computer may be ageneral-purpose computer, a special-purpose computer, a computernetwork, or other programmable apparatuses. The computer instructionsmay be stored in a computer-readable storage medium or may betransmitted from a computer-readable storage medium to anothercomputer-readable storage medium. For example, the computer instructionsmay be transmitted from a website, computer, server, or data center toanother website, computer, server, or data center in a wired (forexample, infrared, radio, or microwave) manner. The computer-readablestorage medium may be any usable medium accessible by the computer, or adata storage device, such as a server or a data center, integrating oneor more usable media. The usable medium may be a magnetic medium (forexample, a floppy disk, a hard disk, or a magnetic tape), an opticalmedium (for example, a DVD), or a semiconductor medium. Thesemiconductor medium may be a solid state drive.

It should be understood that the term “and/or” in this specificationdescribes only an association relationship for describing associatedobjects and represents that three relationships may exist. For example,A and/or B may represent the following three cases: Only A exists, bothA and B exist, and only B exists. In addition, the character “/” in thisspecification generally indicates an “or” relationship betweenassociated objects.

It should be understood that sequence numbers of the foregoing processesdo not mean execution sequences in various embodiments of thisapplication. The execution sequences of the processes should bedetermined based on functions and internal logic of the processes, andshall not constitute any limitation on the implementation processes ofthe embodiments of this application.

Units and algorithm steps in the examples described with reference tothe embodiments disclosed in this specification can be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraints of thetechnical solutions. Different methods may be used to implement thedescribed functions for each particular application, but it should notbe considered that such an implementation goes beyond the scope of thisapplication.

For the purpose of ease and brevity of description, for detailed workingprocesses of the foregoing system, apparatus, and unit, reference may bemade to corresponding processes in the foregoing method embodiments, anddetails are not described herein again.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or may be integrated into another system, or some features maybe ignored or not performed. In addition, the displayed or discussedmutual couplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electrical, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one location, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected depending onactual requirements, to achieve the objectives of the solutions in theembodiments.

In addition, functional units in the embodiments of this application maybe integrated into one processing unit, or each of the units may existalone physically, or two or more units may be integrated into one unit.

When the functions are implemented in a form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer-readable storage medium. Based on such anunderstanding, the technical solutions of this application essentially,or the part contributing to the prior art, or some of the technicalsolutions may be implemented in a form of a software product. Thecomputer software product is stored in a storage medium, and includesseveral instructions for instructing a computer device (which may be apersonal computer, a server, a network device, or the like) to performall or some of the steps of the methods described in the embodiments ofthis application. The foregoing storage medium includes any medium thatcan store program code, such as a USB flash drive, a removable harddisk, a read-only memory (ROM), a random access memory (RAM), a magneticdisk, or a compact disc.

The foregoing descriptions are merely specific implementations of thisapplication, but are not intended to limit the protection scope of thisapplication. Any variation or replacement within the technical scopedisclosed in this application shall fall within the protection scope ofthis application. Therefore, the protection scope of this applicationshall be subject to the protection scope of the claims.

What is claimed is:
 1. A communication method, comprising: receiving, bya terminal device, configuration information from a network device;determining, by the terminal device based on the configurationinformation, N blind detection occasions in a time unit, wherein thetime unit comprises one or more symbols, N is a positive integer, andN≥2; and performing, by the terminal device, blind detection forphysical downlink control channel (PDCCH) in the i^(th) blind detectionoccasion of the N blind detection occasions, wherein i is a positiveinteger, and 1≤i≤N; wherein a total number of blind detections for thePDCCH performed by the terminal device within the time unit is less thanor equal to a maximum number of blind detection in the time unit.
 2. Themethod according to claim 1, further comprising: determining a number ofblind detection in each blind detection occasion of the N blinddetection occasions based on the configuration information.
 3. Themethod according to claim 1, wherein performing the blind detection forthe PDCCH in the i^(th) blind detection occasion comprises: performing,by the terminal device, blind detection for the PDCCH in the i^(th)blind detection occasion based on one or more of the following:configuration information for a control resource set, a search spacetype, a format of downlink control information, an aggregation levelcorresponding to the downlink control information, or serial numbers ofstart control channel elements of a plurality of candidate PDCCHs at asame aggregation level.
 4. The method according to claim 3, wherein theblind detection for the PDCCH in the i^(th) blind detection occasion isbased on the configuration information for the control resource set, andthe control resource set does not span two slots.
 5. The methodaccording to claim 3, wherein the blind detection for the PDCCH in thei^(th) blind detection occasion is based on the search space type; andperforming the blind detection for the PDCCH in the i^(th) blinddetection occasion based on the search space type comprises: performingthe blind detection for the PDCCH in a plurality of search spaces basedon priorities of search space types in the i^(th) blind detectionoccasion; wherein the search space types comprise a common search spaceor a user-specific search space.
 6. The method according to claim 5,wherein a priority of the common search space is higher than a priorityof the user-specific search space.
 7. The method according to claim 1,wherein the maximum number of blind detection in the time unit ispredefined.
 8. A communication apparatus, comprising: a memory,configured to store computer executable program codes; and a processor,configure to execute the program codes; wherein when executed by theprocessor, the program codes cause the communication apparatus to:receive configuration information from a network device; determine,based on the configuration information, N blind detection occasions in atime unit, wherein the time unit comprises one or more symbols, N is apositive integer, and N≥2; and perform blind detection for physicaldownlink control channel (PDCCH) in the i^(th) blind detection occasionof the N blind detection occasions, wherein i is a positive integer, and1≤i≤N; wherein a total number of blind detections for the PDCCHperformed by the terminal device within the time unit is less than orequal to a maximum number of blind detection in the time unit.
 9. Theapparatus according to claim 8, wherein the program codes further causethe apparatus to: determine a number of blind detection in each blinddetection occasion of the N blind detection occasions based on theconfiguration information.
 10. The apparatus according to claim 8,wherein in performing the blind detection for the PDCCH in the i^(th)blind detection occasion, the program codes cause the apparatus to:performing blind detection for the PDCCH in the i^(th) blind detectionoccasion based on one or more of the following: configurationinformation for a control resource set, a search space type, a format ofdownlink control information, an aggregation level corresponding to thedownlink control information, or serial numbers of start control channelelements of a plurality of candidate PDCCHs at a same aggregation level.11. The apparatus according to claim 10, wherein the blind detection forthe PDCCH in the i^(th) blind detection occasion is based on theconfiguration information for the control resource set, and the controlresource set does not span two slots.
 12. The apparatus according toclaim 10, wherein the blind detection for the PDCCH in the i^(th) blinddetection occasion is based on the search space type; and in performingthe blind detection for the PDCCH in the i^(th) blind detection occasionbased on first information, the program codes cause the apparatus to:perform the blind detection for the PDCCH in a plurality of searchspaces based on priorities of search space types in the i^(th) blinddetection occasion, wherein the search space types comprise a commonsearch space and a user-specific search space.
 13. The apparatusaccording to claim 12, wherein a priority of the common search space ishigher than a priority of the user-specific search space.
 14. Theapparatus according to claim 8, wherein the maximum number of blinddetection in the time unit is predefined.
 15. A communication apparatus,comprising: a memory, configured to store computer executable programcodes; and a processor, configure to execute the program codes; whereinwhen executed by the processor, the program codes cause thecommunication apparatus to: send configuration information to a terminaldevice, wherein the configuration information indicate a number N ofblind detection occasions in a time unit, and number of blind detectionsin each of the N blind detection occasions that the terminal device canperform, wherein the time unit comprises one or more symbols, N is apositive integer, and N≥2; and send at least one physical downlinkcontrol channel (PDCCH) in the i^(th) blind detection occasion of the Nblind detection occasions, wherein i is a positive integer, and 1≤i≤N.16. The apparatus according to claim 15, wherein in sending at least onePDCCH in the i^(th) blind detection occasion of the N blind detectionoccasions, the program codes cause the communication apparatus to: sendthe at least one PDCCH in the i^(th) blind detection occasion based onone or more of the following: configuration information for a controlresource set, a search space type, a format of downlink controlinformation, an aggregation level corresponding to the downlink controlinformation, or serial numbers of start control channel elements of aplurality of candidate PDCCHs at a same aggregation level.
 17. Theapparatus according to claim 16, wherein the control resource set doesnot span two slots.
 18. The apparatus according to claim 16, wherein insending at least one PDCCH in the i^(th) blind detection occasion of theN blind detection occasions, the program codes cause the apparatus to:select an available search space based on priorities of search spacetypes in the i^(th) blind detection occasion; and send the at least onePDCCH in the available search space, wherein the search space typescomprise a common search space or a user-specific search space.
 19. Theapparatus according to claim 18, wherein a priority of the common searchspace is higher than a priority of the user-specific search space. 20.The apparatus according to claim 15, wherein the program codes furthercause the apparatus: send first information to the terminal device,wherein the first information comprises at least one of the following:configuration information for a control resource set, a search spacetype, a format of downlink control information, an aggregation levelcorresponding to the downlink control information, or serial numbers ofstart control channel elements of a plurality of candidate PDCCHs at asame aggregation level.